From a black ninja to a thong-wearing sea nymph… Lady Gaga brings the crazy to London’s Roundhouse

After days of rehearsals, Lady Gaga finally took to the stage at the Roundhouse theatre and she certainly didn’t disappoint in the costume stakes.

One minute Gaga, 27, was a black-haired ninja complete with balaclava and eightie’s powerhouse shoulderpads, the next she looked like a nymph of the sea with a shell bikini top and a seaweed encrusted thong giving her once again the chance to show off her derriere.

At the show – which was the first gig in the 20 day calendar of the iTunes Festival – fans watched Gaga perform a few of her most famous songs as well as tracks from her upcoming album ARTPOP.

Earlier in the week, the world was treated to a sneak peek of her latest song Manicure, which she debuted at the fest, via a rehearsal video posted to the star’s Youtube page.

The Applause singer, born as Stefani Joanne Angelina Germanotta, engaged in a choreographed dance routine with her backup crew, who writhed and contorted around her in a sultry and sweaty rendition.

There it is: Lady Gaga fails to see the importance of trousers as she steps on in a shell and seaweed thong

Finish him: Gaga dressed as a black ninja, putting on a black wig and balaclava

Lucky fans: Audience members won tickets to the performance as part of the iTunes Festival which puts on a different concert every day of September

At one point her backup performers raised their arms over their heads and sensually swayed in a wave motion as the pop star unleashed her vocal power with startling force – proving that festival goers are in for a rare treat.

Die hard fans made themselves known outside the venue, dressing up in typical Gaga dashion, taking inspiration from singer’s most famous get-ups.

And to celebrate her new song Swine, many fans donned pig noses and held up signs that said ‘#swinefest2013’.

Quick change: Her dancers hep the singer switch between wigs and outfits onstage

Nice shirt: Gaga’s costume designer ran out of inspiration when it came to this plaid button-up

ARTPOP: Fans dressed up in distressed clown make up to mimic the style worn by Gaga for her new album

On Wednesday she released a minute long snippet of her new song Swine. The lyrics include, ‘I know, I know, I know, I know you want me / You’re just a pig inside a human body / Squeal, squeal, squeal… / You’re just a pig inside, swine.’

She later added a few more Swine lyrics onto her Twitter account: ‘Maybe I should have a little more / Just to stay out of my mind? / ‘Cause it’s when I’m not thinkin’ with you / That I act like a swine.

She is also promoting her new album in the US and the UK and is expected to debut lots of new material during her concert performance this weekend.

She’s got the shells down: Other fans recreate their own looks inspired by the Born This Way singer

Pigs’ nose: Some fans were rocking a pork theme in their costume with blue hair to match

Swinefest 2013: The fans waited patiently outside the Camden venue on Sunday night with the love for Gaga keeping their spirits up